Sub-Saharan African Precipitation Responses to Aerosol Emission Changes

Precipitation changes over sub-Saharan Africa linked to remote aerosol emissions have severely impacted agriculture, ecosystems, and livelihoods historically in the region. Established links between aerosol emissions and precipitation responses impact future projections of sub-Saharan precipitation, which remain uncertain due to differences in model representations of aerosol, aerosol-precipitation interactions, and unclear future aerosol emission pathways. Ongoing large reductions in aerosol emissions from East Asia, combined with uncertainty in future aerosol emissions for India and Africa, indicate that aerosol changes are likely to play an important role in African climate in the near-term future.
In this presentation, we identify regional African precipitation responses to local and remote aerosol emission changes, and establish mechanisms behind them. We focus on responses in the East and West African monsoons, including changes to the intensity, timing, spatial pattern, and variability of rainfall. We also demonstrate the sensitivity of the responses to aerosol emission region, to determine whether local or remote emission changes dominate rainfall responses on seasonal timescales. Using the Regional Aerosol Model Intercomparison Project experiments, we quantify the role of regional aerosol emission changes in near-term African precipitation responses. This allows us to determine the aerosol emission regions which dominate the African precipitation responses, while also exploring sensitivities to absorbing and scattering species of aerosol emissions.
Current analysis has determined that reductions in global aerosol emissions cause West Africa to become significantly hotter and wetter, with a northward shift in precipitation found in some models; this change is strongest along the coastline in most models, though there is considerable diversity in the magnitude of modelled responses.
This work highlights the role of changing aerosol emissions on African precipitation patterns, providing essential information for near-term climate adaptation strategies.